ZWS9 metal door viewer with three-part extending telescopic sleeved collar to suit various door thicknesses from 40-95mm. Traditionally used on thicker cash room doors requiring very high quality of vision to identify personnel before admission. Requires 28mm diameter hole in door (timber or metal) and has 30mm outside lens diameter. Integral hinged security flap fitted internally. With 160° vision for high security doors.Successfully fire tested to BS EN 1634-1: 2014 on steel doors up to 240 minutes integrity. Copy of report available upon request.